Stator used in resolvers, and resolver including same

ABSTRACT

The present invention relates to a stator used in resolvers, in which multiple slots are formed at constant intervals in the circumferential direction and have an excitation coil, a first output coil, and a second output coil are respectively wound around the multiple slots. The excitation coil is wound by a number of windings that is changed on the basis of a sinusoidal wave in accordance with the order of the multiple slots in the circumferential direction. After the first output coil is wound by a number of windings resulting from the division of the total number of windings by a constant ratio, the second output coil is wound, and then the rest of the first output coil is wound.

TECHNICAL FIELD

Exemplary embodiments of the present invention relate to a resolverwhich is a contactless rotation detector, and more particularly, to astator used in resolvers with an improved method of winding coils aroundmultiple slots.

BACKGROUND ART

The present invention relates to a variable reluctance type resolverincluding a stator in which an excitation winding and an output windingare received in multiple slots formed on an annular innercircumferential surface thereof and a rotor disposed to have apredetermined interval from the inner circumferential surface of thestator.

A resolver is a kind of sensor for precisely measuring a rotating speedand a rotating angle of a motor. In particular, a variable reluctancetype resolver to which the present invention belongs has a structure inwhich a coil winding is positioned at a stator and rotors having an ovalor multi-polar salient pole are disposed inside the stator while beingspaced apart from each other at a predetermined interval.

The existing resolver includes a stator 10 as illustrated in FIG. 1.Multiple slots 11 are formed on the inner circumferential surface of thestator 10 while protruding at a predetermined interval in acircumferential direction.

These slots 11 have an excitation coil, a first output coil, and asecond output coil, respectively, wound therearound. As illustrated inFIG. 2, the related art uses a method for simply and sequentiallywinding an excitation coil 12, a first output coil 13, and a secondoutput coil 14 around an outer circumferential surface of a core part 11a of a slot 11.

As a result, even though the second coil 14 is wound at the same numberof windings as the first output coil 13, after the winding operation ofthe first output coil 13 is performed, a larger amount of coil isconsumed in response to a stacked thickness, such that a difference inimpedance between the first output coil 13 and the second output coil 14may occur.

Further, there is a problem in that the existing resolver is sensitiveto harmonics and has a great effect on precision under the externalmagnetic field environment.

Further, the related art forms the excitation coil, the first outputcoil, and the second output coil in the winding pattern as illustratedin FIG. 11A. However, at the time of manufacturing the stator used inresolvers according to the related art, the total number of turns isincreased to obtain a predetermined transformation ratio, and as aresult there is a problem in that manufacturing costs are increased andan analysis of an output signal is complicated.

DISCLOSURE Technical Problem

An object of the present invention is to provide a stator included inresolvers and a resolver including the same capable of reducingsensitivity to harmonics to maintain precision despite a change inexternal magnetic field environment.

Another object of the present invention is to provide a stator includedin resolvers and a resolver including the same capable of savingmanufacturing costs and a manufacturing process.

Still another object of the present invention is to provide a statorincluded in resolvers and a resolver including the same capable ofeasily analyzing an output signal.

Technical Solution

In accordance with one aspect of the present invention, a stator used inresolvers, in which multiple slots are formed at constant intervals in acircumferential direction and have an excitation coil, a first outputcoil, and a second output coil, respectively, wound therearound, whereinthe excitation coil is wound by the number of windings that is changedin a sinusoidal wave form in accordance with an order of the multipleslots in the circumferential direction, the first output coil is woundby the number of windings resulting from the division of the totalnumber of windings by a constant ratio, the second output coil is wound,and then the rest of the first output coil is wound.

In accordance with another aspect of the present invention, a statorused in resolvers, in which multiple slots are formed at constantintervals in a circumferential direction and have an excitation coil, afirst output coil, and a second output coil, respectively, woundtherearound, wherein the first output coil is wound by the number ofwindings resulting from the division of the total number of windings bya constant ratio, the second output coil is wound, and then the rest ofthe first output coil is wound, and the multiple slots are provided in aplurality of even numbers.

In accordance with still another aspect of the present invention, astator used in resolvers, in which multiple slots are formed at constantintervals in a circumferential direction and have an excitation coil, afirst output coil, and a second output coil, respectively, woundtherearound, wherein the excitation coil is wound by the number ofwindings that is changed in a sinusoidal wave form in accordance with anorder of the multiple slots in the circumferential direction and themultiple slots are provided in a plurality of even numbers.

Half of the total number of windings of the first output coil may bewound, the second output coil may be wound, and then the rest of thefirst output coil may be wound.

The winding direction of the first output coil or the second output coilmay be changed by being alternated by a predetermined number inaccordance with an order of the multiple slots in a circumferentialdirection.

The excitation coil may be wound by the number of windings that ischanged in a sinusoidal wave form in accordance with an order of themultiple slots in the circumferential direction, the first output coilmay be wound to have the number of windings changed in the sinusoidalwave form having a phase of +90° relative to a sinusoidal wave of theexcitation coil, and the second output coil may be wound to have thenumber of windings changed in the sinusoidal wave form having a phase of−90° relative to the sinusoidal wave of the excitation coil.

In accordance with yet another aspect of the present invention, a statorused in resolvers, in which multiple slots are formed at constantintervals in a circumferential direction and have an excitation coil, afirst output coil, and a second output coil, respectively, woundtherearound, wherein the first output coil is wound at the same numberof windings in accordance with an order of multiple slots in acircumferential direction by alternating the winding direction by twoslots, the second output coil is wound at the same number of windings inaccordance with an order of multiple slots in a circumferentialdirection by alternating the winding direction by two slots, and theexcitation coil is wound by the number of windings that is changed in asinusoidal wave form in accordance with the order of the multiple slotsin the circumferential direction by a method of alternating the windingdirection by at least two slots.

The first output coil and the second output coil may have a phasedifference of 90°.

The total number of turns of the first output coil or the second outputcoil may be not less than two times or not more than three times thetotal number of turns of the excitation coil.

In accordance with still yet another aspect of the present invention, astator used in resolvers, in which multiple slots are formed at constantintervals in a circumferential direction and have an excitation coil, afirst output coil, and a second output coil, respectively, woundtherearound, wherein a continuous winding number in the same directionof the first output coil and the second output coil (the winding numberin the same direction is a continuous winding number based on the orderof multiple slots in the circumferential direction) is twice or more,and the continuous winding number in the same direction of theexcitation coil is a multiple of the continuous winding number in thesame direction of the first output coil or the second output coil.

The first output coil and the second output coil may have a phasedifference of 90°.

The first output coil or the second output coil may have the samewinding number at each slot.

The continuous winding number in the same direction of the first outputcoil and the second output coil may be equal to or more than threetimes, and the winding number of the first output coil or the secondoutput coil at each slot may have a sinusoidal wave.

The total number of turns of the first output coil or the second outputcoil may be not less than two times or not more than three times thetotal number of turns of the excitation coil.

The winding number of the first output coil or the second output coil ateach slot may have the sinusoidal wave form or the square wave form.

At least 20 slots may be provided.

Advantageous Effects

According to the resolver in accordance with the present inventionhaving the above configuration, it is possible to reduce the sensitivityto harmonics to maintain the precision despite the change in theexternal magnetic field environment.

Further, according to the present invention, it is possible to improvethe shape of the stator to improve the performance of the resolver andsecure the high reliability.

Further, according to the resolver in accordance with the presentinvention as configured above, it is possible to save the manufacturingcosts or the manufacturing process.

Further, according to the present invention, it is possible to easilyanalyze the output signal from the resolver stator.

DESCRIPTION OF DRAWINGS

FIG. 1 is a partial perspective view of a stator used in resolvers.

FIG. 2 is a schematic diagram for describing a stacked structure ofcoils depending on a coil winding for the stator used in resolvers ofFIG. 1.

FIG. 3 is a graph illustrating the number of coil windings wound aroundeach slot of the stator used in resolvers according to the embodiment ofthe present invention.

FIG. 4 is a graph obtained by applying an absolute value to a graphvalue of FIG. 3.

FIGS. 5A and 5B are conceptual diagrams illustrating a winding methodaccording to another embodiment of the present invention forexemplifying a method for winding an excitation coil and first/secondoutput coils according to the spirit of the present invention.

FIGS. 6A and 6B are conceptual diagrams illustrating a simulationconcept of the resolver including the stator according to the presentinvention which is used under the environment that a high magnetic fieldexists and a flux distribution as a result of the simulation.

FIGS. 7A and 7B are graphs illustrating a THD factor result depending onan FFT analysis of a first output signal and a second output signal inthe simulation of FIG. 6A for the stator according to the presentinvention.

FIGS. 8A and 8B are graphs illustrating the THD factor result dependingon the FFT analysis of the first output signal and the second outputsignal in the simulation of FIG. 6A for the stator according to therelated art.

FIG. 9A is a graph illustrating the number of coil windings wound aroundeach slot of the stator used in resolvers according to anotherembodiment of the present invention.

FIG. 9B is a table showing the total number of turns and the number ofpoles related to the number of input turns and the number of outputturns of the excitation coil and the first/second output coils of thestator used in resolvers of FIG. 9A.

FIG. 10A is a graph illustrating the number of coil windings woundaround each slot of a stator used in resolvers according to anotherembodiment of the present invention.

FIG. 10B is a table showing the total number of turns and the number ofpoles related to the number of input turns and the number of outputturns of an excitation coil and first/second output coils of the statorused in resolvers of FIG. 10A.

FIG. 11A is a graph illustrating the number of coil windings woundaround each slot of a stator used in resolvers according to the relatedart.

FIG. 11B is a table showing the total number of turns and the number ofpoles related to the number of input turns and the number of outputturns of an excitation coil and first/second output coils of the statorused in resolvers of FIG. 11A.

EMBODIMENTS

A stator used in resolvers according to an embodiment of the presentinvention basically has a structure as illustrated in FIG. 1 and has anexcitation coil 12, a first output coil 13, and a second output coil 14wound therearound as illustrated in FIG. 2.

However, a method of winding these coils 12, 13, and 14 is different,and therefore the winding method has the following two features.

A first feature relates to the excitation coil 12, in which theexcitation coil 12 is wound depending on a graph value illustrated inFIG. 3. In the graph, a horizontal axis represents an order of a slotand a vertical axis represents the number of windings of the excitationcoils for each slot. In the graph, the excitation coils 12 correspondingto vertical values represented by points on the graph, that is, thenumber of windings are wound around each slot of the horizontal axis inorder.

The number of slots 11 of the stator according to the embodimentrepresented in the illustrated graph is 20. It may be appreciated fromFIG. 3 that all the excitation coils 12 are wound by the number ofwindings changed in a sinusoidal wave form in accordance with an order(1 to 20) of the slots. That is, the excitation coil 2 is wound by thenumber of windings changed in a sine wave form or a cosine wave form andthus the number of windings changes according to a sinusoidal function.In FIG. 3, the number of windings on the graph having a negative (−)value represents that a winding direction is changed to the oppositedirection.

FIG. 4 illustrate a graph modified by taking absolute values of eachgraph to confirm only the number of windings regardless of a directionin which the excitation coil 12 is wound.

FIGS. 5A and 5B illustrate a winding method according to anotherembodiment for exemplifying a method for winding the excitation coil 12and the first/second output coils 13 and 14 according to the spirit ofthe present invention. The illustrated stator has 24 slots, in which 6slots form 1 cycle of a sinusoidal wave for an excitation coil 24.

Meanwhile, in the case of the first output 13 and the second output coil14 wound after the excitation coil is wound, as illustrated in FIG. 5B,half of the total number of windings of the first output coil is wound,the second output coil is wound, and then the rest of the first outputcoil is wound. In this case, half of the total number of windings is notnecessarily wound and the number of windings divided by a constant ratiomay be applied.

According to the above feature, the first output coil is divided intotwo portions by 50% and thus some of the first output coil is firstwound and the rest thereof is wound after the second output coil iswound. FIG. 5B is a conceptual diagram illustrating the orderrelationship, in which a rule of dividing the first output coil into theabove two portions may be variously applied. For example, the number ofwindings for all the slots, respectively, is divided in half, and thushalf of the number of windings is wound around all the slots, after thesecond output coil is wound around all the slots, and then the rest ofthe number of windings may be wound around all the slots. In anotherimplementation, the first output coil of a half of all the slots isfirst wound, the second output coil is wound around all the slots, andthen the first output coil of the rest of the slots may be wound. (forexample, a slot around which the first output coil is wound before thesecond output coil and a slot around which the first output coil iswound after the second output coil may be implemented to be alternate toeach other one by one).

The first output coil and the second output coil may be wound by variousmethods, in the form complying with the rule of winding the first outputcoil and the second output coil.

For example, the number of windings of each slot is the same and thefirst output coil may be wound to have a winding direction (that is,only +/− in the sinusoidal wave form is applied) in the sinusoidal waveform having a phase difference of +90° in the sinusoidal wave form ofthe excitation coil, and the number of windings of each slot is the sameand the second output coil may be wound to have a winding direction(that is, only +/− in the sinusoidal wave form is applied) in thesinusoidal wave form having a phase difference of −90° in the sinusoidalwave form of the excitation coil.

Alternatively, the first output coil may be wound to have the windingdirection in the sinusoidal wave form having the phase difference of+90° in the sinusoidal wave form of the excitation coil and the numberof windings and the second output coil may be wound to have the windingdirection in the sinusoidal wave form having the phase difference of+90° in the sinusoidal wave form of the excitation coil and the numberof windings.

Alternatively, the first output coil 13 and the second output coil 14may alternatively be wound around each slot 11 by changing an order.Alternatively, at least two slots 11 as a unit may be alternativelywound by changing an order.

As described above, all the methods and the order for the windings ofthe first output coil 13 and the second output coil 14 are exemplifiedand various methods which are known or performed may be applied.

FIG. 6A illustrates a simulation concept of the resolver including thestator according to the present invention which is used under theenvironment that a high magnetic field exists and FIG. 6B illustrates aflux distribution as a result of the simulation. In the illustratedsimulation, an object having a high magnetic field of 300 gauss isdisposed right next to the resolver according to the present inventionand as a result of observing a change in magnetic flux of the statordepending on the operation of the resolver, it may be appreciated fromthe present invention that the change in magnetic flux resulting fromthe object of the external magnetic field is small.

The first output signal of the first output coil and the second outputsignal of the second output coil are observed.

FIG. 7A illustrates a THD factor result depending on an FFT analysis ofthe first output signal in the simulation of FIG. 6A for the resolverincluding a stator according to the present invention and FIG. 7Billustrates the THD factor result depending on the FFT analysis of thesecond output signal in the simulation of FIG. 6A for the resolverincluding a stator according to the present invention.

Meanwhile, FIG. 8A illustrates the THD factor result depending on theFFT analysis of the first output signal in the simulation of FIG. 6A forthe resolver including the stator according to the related art and FIG.8B illustrates the THD factor result depending on the FFT analysis ofthe second output signal in the simulation of FIG. 6A for the resolverincluding the stator according to the related art.

Reviewing the THD factor results of FIGS. 7A to 8B, it may beappreciated that in the case of the present invention for the effect ofthe external magnetic field, the maximum THD factor is 0.49 and in thecase of the related art, the maximum THD is 0.72. That is, the resolveraccording to the present invention shows that robustness for theexternal magnetic field is more excellent.

Further, in the experiment of FIG. 6A, according to the spirit of thepresent invention, in the case of the stator having features of theexcitation coil having the number of winding changed in the sinusoidalwave form and/or features of the winding order of the first/secondoutput coils, when more than 20 slots are applied, it is found that theeffect according to the features of the present invention is moreimproved. Further, making the number of slots into 20 numbers or moremay more faithfully implement changing the number of windings in thesinusoidal wave form.

Meanwhile, the present embodiment describes that the excitation coil 12is wound around the slot 11 followed by the first output coil 13 and thesecond output coil 14 but the present invention is not limited theretoand therefore the present embodiment is identically applied even to thecase in which the excitation coil 12 is finally wound around the slot 11after the first output coil 13 and the second output coil 14 are wound.

FIG. 9A is a graph illustrating a winding pattern of the stator used inresolvers according to the embodiment of the present invention and FIG.9B is a table showing the number of poles and the total number of turnsof the stator used in resolvers according to the present embodiment.

In the stator used in resolvers according to the present embodiment, inwhich multiple slots are formed at constant intervals in thecircumferential direction and have the excitation coil, the first outputcoil, and the second output coil, respectively, wound therearound, thefirst output coils are wound at the same number of windings inaccordance with an order of multiple slots in a circumferentialdirection by alternating the winding direction by two slots, the secondoutput coils are wound at the same number of windings in accordance withthe order of multiple slots in the circumferential direction byalternating the winding direction by two slots, and the excitation coilis wound by having the number of windings that is changed in asinusoidal wave form in accordance with the order of multiple slots inthe circumferential direction by a method of alternating the windingdirection by at least four slots.

In the winding structure illustrated, the winding forms of the firstoutput coil and the second output coil are based on 4 slots as oneperiod and the winding form of the excitation coil is based on 20 slots,which is the total number of slots, as one period.

The excitation coil is wound around 10 slots in a positive direction andthe remaining 10 slots are wound in a negative direction and have astructure in which the number of windings is increased in thecircumferential direction to take the sinusoidal wave form and then isgradually reduced.

The excitation coil is wound in the sinusoidal wave form having asinusoidal wave form having a longer period and the first/second outputcoils are wound in the foregoing form at the same number of windings,which has the following advantages.

Further, when the number of input turns is distributed like a sinusoidalwave to distribute a magnetomotive force distribution of a pore in a SINform, the number of output turns may be distributed in a quadrangle,such that the output end may be constantly applied with magnetic fieldintensity.

Further, the excitation coil having the relatively small number ofwindings is allocated with a sinusoidal wave form and the first/secondoutput coils having the large number of windings are wound at the samenumber, such that the winding thickness of each slot may be uniformlyreduced.

Further, a form and a phase of the signal input to the excitation coilare variously applied corresponding to the winding form of theexcitation coil, thereby achieving various effects of the resolver andfacilitating the application to various fields.

Meanwhile, when the second output coil has the same number of windingsbut is observed in the sinusoidal wave form, the phase the second outputcoil may be led by 90° relative to the phase of the first output coil.

Consequently, it is possible to obtain output signals which make it moreconvenient to calculate the rotation speed and the rotating angle of therotating shaft.

In FIG. 9B, the total number of turns of the first output coil and thetotal number of turns of the second output coil each are 1220 and thetotal number of turns of the excitation coil is 524, which is to satisfythe transformation ratio of 0.27. In the above relationship, a valueobtained by multiplying the total number of turns of the excitation coilby the number of poles thereof is still smaller than a value obtained bymultiplying the total number of turns of the first/second output coilsby the number of poles thereof (that is, the number of input turns andthe number of poles<<the number of output turns and the number ofpoles), which may maximize the transformation ratio with the smallernumber of turns than before.

Compared with FIG. 11B which illustrates a table showing the totalnumber of turns and the number of poles related to the number of inputturns and the number of output turns of the excitation coil and thefirst/second output coils of the stator used in resolvers according tothe related art so as to obtain the same transformation ratio of 0.27,the foregoing advantages may be confirmed.

The total number of turns of the first/second output coils according tothe present embodiment is preferably not less than two times or not morethan three times the total number of turns of the excitation coil. Thismay obtain a widely used transformation ratio, secure the stableoperation of the resolver detection, and save the total number of turns.

In the case of the stator used in resolvers illustrated, the continuouswinding frequency in the same direction of the first/second output coils(the winding in the same direction is a continuous frequency based onthe order of multiple slots in the circumferential direction) is twiceand the continuous winding frequency in the same direction of theexcitation coil is ten times. However, in another implementation, thecontinuous winding frequency in the same direction of the first/secondoutput coils may be equal to or more than three times and the continuouswinding frequency in the same direction of the excitation coil may betwo times more than the continuous winding frequency in the samedirection of the first/second output coils. For example, when thecontinuous winding frequency in the same direction of the first/secondoutput coils is three times, the continuous winding frequency in thesame direction of the excitation coil may be a frequency which is equalto or more than six times.

Further, in the case of the stator having features of the excitationcoil having the number of windings changed in the sinusoidal wave formaccording to the spirit of the present embodiment and/or features of thewinding order of the first/second output coils having the patternchanged in a pulse form at the same number of windings, when the numberof slots is equal to or more than 18, and preferably is equal to or morethan 20, it was confirmed that the foregoing effects according to thefeatures of the present invention are more improved.

The stator used in resolvers according to another embodiment basicallyhas the structure as illustrated in FIG. 1. As illustrated in FIG. 2,the stator has the excitation coil 12, the first output coil 13, and theoutput coil 14 wound therearound and the method for winding coils 12,13, and 14 is similar to that of the first embodiment simply but thewinding patterns of the first/second output coils are differentiatedfrom each other depending on the sinusoidal wave form.

FIG. 10A is a graph illustrating the winding pattern of the stator usedin the resolvers according to the present embodiment and FIG. 10B is atable showing the number of poles and the total number of turns of thestator used in the resolvers according to the present embodiment.

In the stator used in resolvers according to the present embodiment, inwhich multiple slots are formed at constant intervals in thecircumferential direction and have the excitation coil, the first outputcoil, and the second output coil, respectively, wound therearound, thecontinuous winding frequency in the same direction of the first/secondoutput coils (the winding in the same direction is a continuousfrequency based on the order of multiple slots in the circumferentialdirection) is equal to or more than three times and the continuouswinding frequency in the same direction of the excitation coil is equalto or more than twice of the continuous winding frequency in the samedirection of the first output coil or the second output coil.

Here, the winding patterns of the first output coil and the secondoutput coil may have the sinusoidal wave form. In the case of the statorused in resolvers illustrated, the continuous winding frequency in thesame direction of the first/second output coils (the winding in the samedirection is a continuous frequency based on the order of multiple slotsin the circumferential direction) is three times and the continuouswinding frequency in the same direction of the excitation coil is ninetimes, and therefore for the winding patterns of the first/second outputcoils to have the sinusoidal wave form, the winding frequency of themiddle slot among the three slots is most and the winding frequency ofboth slots other than the middle slot may be implemented to be equal toeach other.

Meanwhile, in another implementation, the continuous winding frequencyin the same direction of the first/second output coils may be equal toor more than four times and the continuous winding frequency in the samedirection of the excitation coil may be two times more than thecontinuous winding frequency in the same direction of the first/secondoutput coils. For example, when the continuous winding frequency in thesame direction of the first/second output coils is four times, thecontinuous winding frequency in the same direction of the excitationcoil may be a frequency which is equal to or more than four times.

In FIG. 10A, the continuous winding frequency in the same direction ofthe first/second output coils is four time and the continuous windingfrequency in the same direction of the excitation coil is twelve times.The total number of slots of the stator is 24, the number of poles ofthe first/second output coils is 6, and the number of poles of theexcitation coil is 2.

The stator used in resolvers according to the present embodiment havingthe above configuration may detect the signal for calculating therotating speed and the rotating angle of the rotating shaft by aninduction phenomenon between the excitation coil having the windingpattern in the sinusoidal wave form having a longer period and thefirst/second output coils having the winding patterns in the sinusoidalwave form having a shorter period.

Therefore, compared with the embodiment 1, the manufacturing process maybe slightly complicated but may enhance the differentiation of a phasedetection signal of the resolver by the winding pattern of thesinusoidal wave of the excitation coil and the output coil.

Meanwhile, in the relationship of the first/second output coils havingthe winding patterns in the sinusoidal wave form having the same periodas each other, the phase of the second output coil may be led by 90°relative to that of the first output coil.

Consequently, it is possible to obtain the output signals which make itmore convenient to calculate the rotation speed and the rotating angleof the rotating shaft.

Further, according to the spirit of the present invention, in the caseof the stator having features of the excitation coil having the numberof winding changed in the sinusoidal wave form and/or features of thewinding order of the first/second output coils, it is found that theeffect according to the features of the present invention is moreimproved when more than 18 slots are applied. Further, making the numberof slots into 18 numbers or more, preferably, 24 numbers or more maymore faithfully implement changing the number of windings of theexcitation coil and the first/second output coils in the sinusoidal waveform.

The foregoing embodiments describes that the excitation coil 12 is woundaround the slot 11 followed by the first output coil 13 and the secondoutput coil 14 but the present invention is not limited thereto andtherefore the present embodiment is identically applied even to the casein which the excitation coil 12 is finally wound around the slot 11after the first output coil 13 and the second output coil 14 are wound.

Further, the foregoing stator used in resolvers and the resolverincluding the same are only an example to help understand of the presentinvention and therefore it is not to be construed that the scope and thetechnical scope of the present invention are not limited to theforegoing description.

The scope and the technical scope of the present invention are definedby claims and the equivalent scope thereof to be described below.

1-16. (canceled)
 17. A stator used in resolvers, in which multiple slots are formed at constant intervals in a circumferential direction and have an excitation coil, a first output coil, and a second output coil, respectively, wound therearound, wherein the excitation coil is wound by the number of windings that is changed in a sinusoidal wave form in accordance with an order of the multiple slots in the circumferential direction, the first output coil is wound by the number of windings resulting from the division of the total number of windings by a constant ratio, the second output coil is wound, and then the rest of the first output coil is wound.
 18. A stator used in resolvers, in which multiple slots are formed at constant intervals in a circumferential direction and have an excitation coil, a first output coil, and a second output coil, respectively, wound therearound, wherein the first output coil is wound by the number of windings resulting from the division of the total number of windings by a constant ratio, the second output coil is wound, and then the rest of the first output coil is wound, and the multiple slots are provided in a plurality of even numbers.
 19. A stator used in resolvers, in which multiple slots are formed at constant intervals in a circumferential direction and have an excitation coil, a first output coil, and a second output coil, respectively, wound therearound, wherein the excitation coil is wound by the number of windings that is changed in a sinusoidal wave form in accordance with an order of the multiple slots in the circumferential direction and the multiple slots are provided in a plurality of even numbers.
 20. The stator used in resolvers of claim 17, wherein half of the total number of windings of the first output coil is wound, the second output coil is wound, and then the rest of the first output coil is wound.
 21. The stator used in resolvers of claim 17, wherein the winding direction of the first output coil or the second output coil is changed by being alternated by a predetermined number in accordance with an order of the multiple slots in a circumferential direction.
 22. The stator used in resolvers of claim 17, wherein the excitation coil is wound by the number of windings that is changed in a sinusoidal wave form in accordance with an order of the multiple slots in the circumferential direction, the first output coil is wound to have the number of windings changed in the sinusoidal wave form having a phase of +90° relative to a sinusoidal wave of the excitation coil, and the second output coil is wound to have the number of windings changed in the sinusoidal wave form having a phase of −90° relative to the sinusoidal wave of the excitation coil.
 23. A stator used in resolvers, in which multiple slots are formed at constant intervals in a circumferential direction and have an excitation coil, a first output coil, and a second output coil, respectively, wound therearound, wherein the first output coil is wound at the same number of windings in accordance with an order of multiple slots in a circumferential direction by alternating the winding direction by two slots, the second output coil is wound at the same number of windings in accordance with an order of multiple slots in a circumferential direction by alternating the winding direction by two slots, the excitation coil is wound by the number of windings that is changed in a sinusoidal wave form in accordance with the order of the multiple slots in the circumferential direction by a method of alternating the winding direction by at least two slots.
 24. The stator used in resolvers of claim 23, wherein the first output coil and the second output coil have a phase difference of 90°.
 25. The stator used in resolvers of claim 23, wherein the total number of turns of the first output coil or the second output coil is not less than two times or not more than three times the total number of turns of the excitation coil.
 26. A stator used in resolvers, in which multiple slots are formed at constant intervals in a circumferential direction and have an excitation coil, a first output coil, and a second output coil, respectively, wound therearound, wherein a continuous winding number in the same direction of the first output coil and the second output coil (the winding number in the same direction is a continuous winding number based on the order of multiple slots in the circumferential direction) is twice or more, and the continuous winding number in the same direction of the excitation coil is a multiple of the continuous winding number in the same direction of the first output coil or the second output coil.
 27. The stator used in resolvers of claim 26, wherein the first output coil and the second output coil have a phase difference of 90°.
 28. The stator used in resolvers of claim 26, wherein the first output coil or the second output coil has the same winding number at each slot.
 29. The stator used in resolvers of claim 26, wherein the continuous winding number in the same direction of the first output coil and the second output coil is equal to or more than three times, and the winding number of the first output coil or the second output coil at each slot has a sinusoidal wave form or a squared wave form.
 30. The stator used in resolvers of claim 29, wherein the total number of turns of the first output coil or the second output coil is not less than two times or not more than three times the total number of turns of the excitation coil.
 31. The stator used in resolvers of any one of claims 17 to 20, 23 or 26, wherein at least 20 slots are provided.
 32. A resolver including the stator used in resolvers of any one of claims 17 to 20, 23, or
 26. 